findPeaks() implemented for LineScan

I have implemented the findPeaks() method for LineScan objects.
This method returns the peaks in form of a list of (peak position, peak value) tuples.

EXAMPLE:

    ls = img.getLineScan(x=150)
    peaks = ls.findPeaks()
    print peaks
    """
    output:
    [(78, 153),
    (123, 127),
    (202, 143),
    (234, 140),
    (288, 129),
    (349, 175),
    (402, 151),
    (455, 166)]
    """